Many refractory metal powders (Ta, Nb, Ti, Zr, etc) are made by hydriding an ingot of a specific material. Hydriding embrittles the metal allowing it to be easily comminuted or ground into fine powder. The powder is then loaded in trays and placed in a vacuum vessel, and in a batch process is raised to a temperature under vacuum where the hydride decomposes and the hydrogen is driven off. In principle, once the hydrogen is removed the powder regains its ductility and other desirable mechanical properties. However, in removing the hydrogen, the metal powder can become very reactive and sensitive to oxygen pickup. The finer the powder, the greater the total surface area, and hence the more reactive and sensitive the powder is to oxygen pickup. For tantalum powder of approximately 10-44 microns in size after dehydriding and conversion to a true Ta powder the oxygen pickup can be 300 ppm and even greater. This amount of oxygen again embrittles the material and greatly reduces its useful applications.
To prevent this oxygen pickup the hydride powder must be converted to a bulk, non hydride solid which greatly decreases the surface area in the shortest time possible while in an inert environment. The dehydriding step is necessary since as mentioned previously the hydride is brittle, hard and does not bond well with other powder particles to make usable macroscopic or bulk objects. The problem this invention solves is that of converting the hydride powder to a bulk metal solid with substantially no oxygen pickup.